1. Field of the Invention
The present invention relates to a battery reclamation system. More particularly, the present invention relates to a battery reclamation system for recycling batteries, and especially batteries having mercury-zinc, mercury-cadmium or silver-zinc.
2. Description of the Related Art
Mercury-zinc and mercury-cadmium batteries contain mercury, which is a land-banned hazardous waste. These batteries are constructed of multiple button cells that are encased in metal, cardboard or epoxy-filled plastic casings or housings. Mercury-zinc batteries include the 9.8-volt, Mark 95, Mark 130, Mark 131, Mark 135 and Mark 141 batteries. The mercury-zinc button cells are primary, non-rechargeable batteries that operate based on the zinc-mercuric oxide system. Mercury-cadmium batteries include the Mark 117 and Mark 121 batteries. The mercury-cadmium button cells are primary batteries that operate based on the cadmium-mercuric oxide system.
Silver-zinc battery cells contain significant amounts of silver and small amounts of mercury. However, the battery owner is not compensated for the silver that is in the batteries, and the owner must purchase new silver for replacement batteries. Mercury-containing silver-zinc batteries include the Mark 53 Modification (Mod) 1, Mark 46 and LR 190 batteries. Each cell has a plastic case with a series of silver and zinc electrodes immersed in an electrolyte solution.
The cell components for the silver-zinc batteries are housed in a plastic case that contains a series of silver and zinc electrode plates, separated by membranes. To activate the cell, the electrodes are immersed in a potassium hydroxide KOH solution. Each membrane separator consists of a cellophane main separator and nylon mesh or felt interseparators. The main separators prevent shorting of the battery by separating the plates, but allow electron transfer through the electrolyte. The interseparators provide space to allow contact between the electrolyte and the plate.
The Mark 53 cells come in two configurations, one by Yardney and the other by BST. The Yardney cell is constructed using a normal wrap assembly, where the silver electrodes are wrapped in membrane separators, and the zinc electrodes are placed in between the wrapped silver plates. The BST cell is constructed using a split wrap assembly, where the silver electrodes are wrapped in membrane separators, and the zinc electrode is also wrapped in a membrane separator and placed between the silver plates.
Silver-zinc cells can be wetted and very spent. These cells have been used and recharged several times, resulting in corrosion and very complete chemical reactions within the cells. It is very difficult to delineate the interior components in these cells. In addition, silver-zinc cells can be used with varying liquid content. These cells have been wetted and used. However, they have not been recharged as many times and are not severely spent. It is possible to easily delineate the interior components of these cells. These cells contain varying amounts of KOH solution, including very wet, slightly wet, and dried out used cells.
In view of the foregoing, one object of the present invention is to develop a system and method for isolating and recovering the mercury from mercury-zinc, mercury-cadmium and silver-zinc batteries. A further object is to develop a battery reclamation system that recovers silver from silver-zinc batteries for resale or reuse of the silver. Another object is to reduce liability related to handling and disposing of batteries as hazardous waste by performing the recycling activities in a controlled environment. Yet another object of the invention is to provide a method for recycling mercury-cadmium batteries. Still another object is to provide a battery reclamation system that is flexible to accommodate new battery types.
Accordingly, a reclamation system is provided for mercury-zinc and mercury-cadmium battery disassembly. The reclamation system has a cooling or freezing station, a cracking station, a disassembly station and a shredder station. The cooling station freezes the batteries to facilitate cracking of the housing and internal epoxy by the cracking station. The cracked batteries are then disassembled and the battery cells are shredded. The shredded cells are placed in the retort oven, for recovery of mercury.
In an alternative embodiment of the invention, a reclamation system is provided for silver-zinc battery disassembly. The reclamation system has a staging and draining station, cracking station and a disassembly station. At the staging and draining station, wet batteries are separated out and drained. The batteries are then cracked and disassembled. The cells are placed in the retort oven, for recovery of mercury.